Gelb Science Center -- Phillips Academy

Radon in buildings has been a persistent problem first identified by health workers more than five decades ago. The most common source for radon is actually water from wells that passes into buildings in the form of steam. Radon is a naturally occurring gas generated from layers of granite underground and is the product of radioactive decay. In open air, radon does not present a problem as it is so diluted that it does not affect the lungs.

Phillips Academy in Andover, Massachusetts, had moved a campus house in order to build the new Gelb Science Center. Before the house was moved, the radon in the building was measured at more than 4,000 picocuries - 1000 times higher than that allowed by the EPA. With this knowledge, the architect, Kallmann McKinnell and Wood proceeded to investigate various remedies for the new foundation.

Resicon USA was brought in by the architect to provide practical field consulting and design services. When Resicon USA started the project, 12 fields of underslab vent piping were already designed to actively vent the radon from the slab and up though the roof of the center. Resicon's engineers compared the long-term cost of operating such a venting system to actually eliminating much of the piping and fans associated with the vent system and deploying a simpler solution.

Resicon recommended a combination system of Ecoline-S spray-on liner (by Epro Services, Derby, Kansas), 2-part urethane coatings and 60 mil high density polyethylene liner (manufactured by GSE Environmental of Houston, Texas) for the entire area under both the basement, first floor slabs and tunnelways, and for any walls that were adjacent to these occupied spaces.

Additional issues were the large amount of small electrical, water and gas conduits that penetrated the liner in clusters of up to 20 conduits spaced ¾ inch (2 cm) apart, plus all plumbing and other penetrations. Resicon also addressed the backflow of radon from new manholes installed on the site which connected to the municipal sewers.

Resicon designed special systems for all piping and conduits so that the seals were complete and redundant. First, the pipes were caulked around the base, then the liner was heated and pulled over the pipe to meet the caulking, then special tape was applied to the lip of the extended liner, and finally the liner was clamped to the pipe. This system worked in 98 percent of the situations which allowed the subcontractor, , to maintain the schedule required by the general contractor, Erland Construction of Burlington, Massachusetts. Manholes were fitted with tide valves.

The liner system was locked onto the walls by Poly Lock, also manufactured by GSE. This system, after welding the liner to the embedded Poly Lock, was covered with a urethane coating so that imperfections in the concrete pour and shrinkage of the concrete itself would not affect the integrity of the barrier system over time.

The project was completed and certified in the summer of 2003 with 100% radon mitigation without any building ventilation.